How to make a bill of materials and avoid the mistakes

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If you work in manufacturing, you’ve undoubtedly heard about the importance of creating a Bill of Materials (BOM) for each of the products your business produces.

That being said, creating a Bill of Materials is a little more complicated than just sitting down and listing the components and raw materials you use in manufacturing. To create a truly accurate and useful BOM will require more effort and consideration, but the work is worth it. A detailed BOM will provide deep insights into your manufacturing process and can even help you spot issues before they blossom into full-blown problems.

Today, we’ll walk you through the steps of creating your very own Bill of Materials. From the questions you’ll need to consider before you get started to the actual step-by-step process of putting it all together, we’re here to help you navigate the process.

What is a Bill of Materials? 

A Bill of Materials is a document that lists all the materials required to make a product, along with the quantity of the items required.

This includes all components of the manufacturing process, from raw materials to consumables to subassemblies and intermediate materials. In simple terms, if it’s used to make the product, it goes on the BOM.

The BOM does not break down the actual manufacturing process, but is instead presented in a structured way that may correlate with some of the steps in your production process.

There are two types of BOM: the EBOM and the MBOM. Let’s discuss both.

  • EBOM

The EBOM is the Engineering Bill of Materials. This Bill of Materials is used when a product is still being developed and is revised with each new product iteration during the research and development phase.

  • MBOM

The MBOM is the Manufacturing Bill of Materials (or the Mass Production Bill of Materials in some circles). You’ll develop this document when a product has finished the research and development phase and is ready for mass production and sale to the public.

These two different types of Bill of Materials documents can have different structures and formatting depending on who’s creating and using them. The key takeaway here is to simply recognize that there are different types of BOMs and when they’re used.

4 key questions to answer before creating a bill of materials

Now that we have a detailed Bill of Materials definition, you might feel like you’re ready to dive in and start creating.

Before you do, we should talk about four very important questions you need to answer before creating your BOM. 

Answering these questions now can save you time and headache down the road.

1. Will you track consumables?

When you create your BOM, it’s common to think about all of the components that actually make up your product. Tracking the nuts, bolts, materials, and other components feels like a complete Bill of Materials.

However, many companies fail to consider the consumables that go into manufacturing. Does your product use glue to hold things together? Nails? Are you tracking those items too?

If you’re like most companies, you’re probably not, but you should be. 

The BOM should include everything that goes into manufacturing your product. If it’s not included on the BOM, it might not find its way into the finished product.

Ultimately, the decision about whether or not to track consumables is up to you. , but make this decision before you start creating a BOM and then be consistent with it moving forward.

2. Will you attach files to your BOM?

Some companies want a BOM that is a pared down document consisting solely of the items that are utilized in the manufacturing process.

Others like to attach extra relevant documents to their Bill of Materials so that anyone using the document can find additional information without having to go search for it.

The additional information can be any number of things, from CAD drawings, material data sheets, spec guides, assembly information, and so on.

What matters here is not what the materials are, but whether or not you’ll choose to attach them to your BOM and how you will attach them if you do. If you do include additional materials, come up with a system for doing so, and be consistent across your BOMs.

3. Who will use the BOM?

As product manufacturing can spread across a large number of departments at your company, it’s important to think about who will be using your BOMs so that you can build them accordingly.

For example, the BOM is a manufacturing document but marketing, sales, and other departments may use it at different times.

If you’ve created a BOM solely for the manufacturing team or your engineers, then it’s probably not going to be as useful to other departments at your company. 

Think about everyone who may use your Bill of Materials. It’s better to include things that will make it more accessible than to make it overly technical and limit who can benefit from it. 

Knowing who the document is designed for before creating it can save you from having to continually refine it over time.

4. Will you track various BOM versions?

Earlier, we discussed EBOMs and MBOMs. In the EBOM stage, it’s not uncommon for your team to create multiple BOMs, or multiple revisions of the BOM as the product is refined.

The question then becomes what do you do with those older BOMs?

Some companies will scrap them, keeping only the current BOM on hand for the manufacturing team. 

That being said, keeping the old BOMs can actually be valuable as it provides an evolutionary “fossil record” of your product’s development. Just be sure to store them in such a way that there’s no confusion as to which BOMs are early and outdated and which one is the current one that should be used.

Create a successful bill of materials with these 8 tips 

Once you’ve answered the questions in the previous section, it’s now time to start building your very own BOM. 

To help make the process as easy and painless as possible, we’ve included eight tips. Follow these and you’ll have a useful, well-designed Bill of Materials that will streamline your manufacturing process.

1. Build the BOM to suit your project

If you were hoping there was a one size fits all template for creating a BOM, we’ve got some bad news. 

Your BOM is a fluid document that should be constructed with the needs of the specific project in mind. In fact, BOMs for two different products from the same company might actually look radically different depending on what the product is, who might need to utilize the BOM, and so on. 

We get it. The idea of creating a BOM template where you simply plug in new materials and quantities for every new project sounds appealing. There may be instances where you can do that. However, it’s always in your best interest to build the BOM to suit the needs of the project, not try to shoehorn the project into your previous BOM’s format.

2. Use a template when possible

Wait, didn’t the last point say to build a BOM to suit each project?

While there will be instances where you need to build a brand new BOM from scratch, there will likely be more times where you can create a new product’s BOM by making some minor adjustments to a previous Bill of Materials. 

Beyond that, it’s good to have a general template for your BOMs so that anyone creating one will know where additional documents/information are stored, whether or not your BOMs should track consumable materials, and so on.

The key thing to remember here? It’s great to have a template for your BOMs. Just don’t become slavishly devoted to it to the point where you’re afraid to create a new BOM when the project calls for it.

3. Don’t go overboard with the details

There can be a tendency to try to include everything but the kitchen sink in a BOM, especially when you’re trying to guess at the needs of every person who might read it.

Resist the urge to overload the BOM with information. This should be a relatively simple document wherein people can find the information they need without having to wade through hundreds of pages of less relevant material.

On the other side of this coin, don’t skimp on the information either. The BOM is a list of materials, but just rattling off components and numbers isn’t particularly useful either.

Like so many things in life, a good BOM is about finding the balance: here it’s between too much information and too little.

4. What to include in a BOM 

Building on that last tip, here are some of the things that you absolutely should include in your Bill of Materials if you want it to be useful.

If you hit these things and nothing else, you will be in a good position as far as striking the balance between too much and too little information. 

  • Part Number
  • Manufacturer Name
  • Part Name & Description

These first three items ensure your manufacturing team knows exactly what parts they need, and who makes the part.

  • Quantity

Quantity is one of the most important pieces of info on the BOM. This allows you to understand how much of an item you’ll need, which is incredibly useful when negotiating rates on bulk orders or simply deciding how much inventory to have on hand.

  • Procurement Type

Most companies break down their procurements by using a P, M, or C. P is for things that are purchased, M is for modified, and C is for custom label.

  • Priority Analysis

Here you’ll want to prioritize your materials. Which ones are the most important? Which ones are less important?

  • Alternate Parts 

If for some reason you cannot get the parts you need, here is where you’d list acceptable alternatives.

  • Part Level 

The part level designation simply refers to the main assembly, sub assembly, and component. This way parts end up in the right place during the manufacturing process.

  • File Availability

If you attach files to the BOM, this is where they’re included. Are you offering CADs? Drawings? Other information? This is where it belongs.

  • Revision Level

If you have multiple versions of a BOM, it’s important to note what changes have been made from previous iterations.

  • Comments & Notes 

This section is a great place to note any changes, issues, or other potentially important information other users of the document could need to know.

5. Double check everything

A BOM becomes significantly less useful if the information it contains is inaccurate. Because of this, it’s vital to double-check the document to ensure errors don’t slip through.

It’s even better if you can get other people to do the double-checking. Fresh eyes spot mistakes you might have otherwise missed.

6. Track changes

It’s a given that your BOM will evolve over time. Things change, and those changes will be reflected in the document. This is why it’s imperative that you diligently track changes to your BOM.

This way, users will know they have the most current document, but can also refer to earlier versions when the situation calls for it.

7. Limit access

Your BOM will be utilized by a lot of different people at your company. However, not all of those people need to have access to editing your BOM.

To keep things neat, orderly, and accurate, you will need to limit the number of people who can make changes to your BOM.

8. Automate whenever possible

Inventory management software can help you make managing your BOMS significantly easier.

Automation tools like software can find discrepancies, make sure you always have enough materials on hand, and can help make managing BOM revisions and new versions significantly easier.

Final thoughts

If you manufacture the products you sell, then you’re probably already well aware of just how valuable a Bill of Materials is for your business.

A good BOM fulfills a lot of duties, including making sure your manufacturing process works smoothly.

Creating a BOM is not an overly complicated proposition, but there are tips and tricks that can help you create an even more useful document. Using the advice inn this article can not only make creating your BOM easier, but it can ensure you create a more useful document in the process.

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